LONDON — Life just keeps on getting bigger and better for Missy Franklin, the teenage swimming sensation whose fame is quickly spreading beyond the Olympic pool.

Even Bieber's a believer.

The 17-year-old girl with the can't-miss smile and catchy "Missile Missy" nickname is cheerily living up to the outsized expectations that were heaped on her going into her first Olympics.

Franklin won a gold medal — even before Michael Phelps — in the 100-meter backstroke Monday after having opened her games with a relay bronze.

And a certain teen idol took notice.

"Heard (at)FranklinMissy is a fan of mine," singer Justin Bieber tweeted Tuesday. "Now I'm a fan of hers too! CONGRATS on winning GOLD! (Hashtag)muchlove."

"I just died," Franklin tweeted in response. "Thank you!"

She's still got five more events to go, giving her plenty of chances to leave London as America's big star with Phelps heading into retirement. His underwhelming performances so far and Ryan Lochte's failure in his last two events have swung the spotlight squarely on Franklin.

Franklin barely missed a bronze medal in the 200 freestyle on Tuesday night. She finished fourth, just one-hundredth of a second off the podium.

"It's definitely hard when I was so close," she said.

A night earlier, she qualified for the 200 free final just 14 minutes before she won the first gold medal of what promises to be a stellar career.

"What kind of high school kid can do that?" marveled teammate Breeja Larson.

Franklin finished the semis of the 200 free on Monday night, then raced to the diving well for a quick warmdown. There was no time to make it to the practice pool before her bigger race.

"That was fantastic. She did it exactly right," said Bob Bowman, Phelps' coach.

No less an authority on doubling up than Phelps was amazed at her stamina. He estimated his tightest time between races at a major meet was about 30 minutes.

"She's a racer and she knows what to do," he said, having long ago paid Franklin the ultimate compliment to a swimmer: "She's a stud."

At 6-foot-1, with big hands and size 13 feet, Franklin cuts an imposing figure on the starting blocks. And — Bieber take note — her size is no impediment to her dancing skills.

She shows them off in the U.S. swimming team's recent video spoof to "Call Me Maybe." Franklin boogies down the aisle of a plane and whips her long brown hair around while lip-synching to the Carly Rae Jepsen tune that has inspired countless viral videos.

Franklin has cracked up her teammates since last summer, when she won three gold medals in her first world championships in China and set two American records in the process. They were amused by her excited approach to swimming the mundane morning prelims and her bubbly personality.

She's been even more enthusiastic — if that's possible — at the Olympics. She loves her apartment in the athletes village and was thrilled at the prospect of taking home the comforter on her bed. "They're so cute," she gushed.

"She is always smiling, always positive," Larson said. "You will never hear a negative thing out of her mouth."

Franklin showed up for the medalists' news conference with the gold medal stuffed in the pocket of her gray warmup jacket. When someone asked where it was, she quickly pulled it out and slipped the purple ribbon it hangs from around her neck.

"Isn't it pretty?" she said.

She figures to have many more to admire in the future.